[1.12.x] Cryogenic Engines: Liquid Hydrogen and Methane Rockets! (August 13, 2024)

[Nertea]

CryoEngines 2.0.2

• KSP 1.12
• Updated B9PartSwitch to 2.18.0
• Updated DeployableEngines to 1.3.1
• Updated CryoTanks to 1.6.1
• Updated DynamicBatteryStorage to 2.2.4
• Fixed gimbal response speed flag missing on all engines
• Fixed Eagle and Harrier masses: they were swapped before

[Skystorm]

@Nertea I am finding that a couple of the engines have some non-trivial thrust torque.  I wonder if maybe you had some time to take a look.

MU-4U "Vulture" is showing 1,000 KN of vacuum thrust but 718 Nm of thrust torque.

MU-11 "Harrier" is showing 296 KN of vacuum thrust but 68 Nm of thrust torque.

MR-8 "Allosaur" is showing 1,850 KN of vacuum thrust and 8 Nm of thrust torque.  May not be worth fixing but figured I would mention it anyway.

All of the remaining engines are between 0 - 2 Nm.

[Rakete]

Boattail-Shrouds of some cryo engines (e.g. Erebus) are slightly off centre and/or not perfectly point symmetric:

If you put tail fins on your rocket and mound them on the boat tail (even if using radial symmetry) this will induce drift of the rocket to one side. If you mount the fins on the tank above the engine and offset them downwards, the effect is gone. So if you want to use these boat tails in atmosphere, don't mount the rocket's tail fins there. Mount them on tanks, that are perfect circular, or you have to fight induced forces to one side.

Anyway... something is odd there, and might be worth having a look. (can't post it to github right now... sorry.)

Edited July 31, 2021 by Rakete

[Nertea]

13 hours ago, Rakete said:

Boattail-Shrouds of some cryo engines (e.g. Erebus) are slightly off centre and/or not perfectly point symmetric:

 

With things like this 'some' isn't very helpful, I need to know exactly which in order to track it down. I've done a pass through and think I've identified something in a few meshes that might cause this but I am not sure. 

CryoEngines 2.0.3

• Fixed compression format for some engine textures
• Fixed Prometheus nozzle collider not moving with gimbal
• Inspected and adjusted thrust transform centres for all engines, some fixes made
• Inspected and adjusted surface attach colliders for all engines, some fixes made

 

 

[Rakete]

7 hours ago, Nertea said:

With things like this 'some' isn't very helpful, I need to know exactly which in order to track it down.

Understood. I noticed this twice and unfortunatly didn't write the engine type down, the first time i saw it. I should always put pen and paper next to me 

It definitely happend to the erebus.

Edited August 1, 2021 by Rakete

[Rakete]

@Nertea

Update: I managed to test CE 2.0.3 in my 1.11.2 install, just by dropping the CE-Folder in, without replacing the other updated dependency folders (they contain dlls, which i assume to be compiled against 1.12 - so that I'll update them when I move over to KSP 1.12).

The above mentioned centre of thrust and surface attachment issues seem to be gone (tested on Erebus). Thank you.

Edited August 1, 2021 by Rakete

[Nertea]

Thanks for checking, glad it fixed it.

 

[Lucas_R]

On 4/29/2015 at 1:06 PM, Nertea said:

KSP 1.12.x

Cryogenic Engines [2.0.3]  Last Updated July 31, 2021

This modest part pack is designed to provide some new rocket engines that run either Liquid Hydrogen and Oxidizer or Liquid Methane and Oxidizer.

Liquid Hydrogen Engines

There are nine models provided, two in each of the 1.25, 1.875, 2.5 and 3.75m sizes and one in the 0.625,. These engines have better fuel efficiency than the KSP stock engines, up to 460s of Isp, but beware! They're more expensive and produce less thrust per unit weight. In addition, liquid hydrogen is less dense than liquid fuel, so for the same Delta-V, you will need more tank volume.

Liquid Methane Engines

There are ten  models provided, two in each of the 0.625, 1.25, 1.875, 2.5 and 3.75m sizes. These engines sit between the Liquid Hydrogen and Liquid Fuel options in terms of efficiency, and don't have as much of a tank volume penalty. 

To store your new fuels, I've provided ModuleManager/B9PartSwitch configs that allow you to change the contents of stock tanks between LF/O, LH2/O, LCH4/O, LF, O,  LH2 and LCH4. These should work with most mod tanks, but no promises. However, Liquid Hydrogen is very temperamental and without the proper storage it will slowly evaporate ("boil off"). You can activate cooling on all added tanks for a modest cost in Electric Charge, but this is inefficient. Therefore, I provide special cryogenic tanks bundled with the mod which have insulation to reduce the cost of cooling the tanks. Liquid Methane will also boil off, but more slowly than Liquid Hydrogen. 

This mod is designed to synergize well with Kerbal Atomics, and with the various Near Future Technologies mods I make. It is also fully integrated into the Community Tech Tree.

Full Screenshot Gallery

Frequently Asked Questions Q: Will you add feature/part xxx? A: The mod is feature complete and I am unlikely to do any more development Q: Oxidizer isn't LOX, it's something else! A: You are completely free to do whatever you like and change it  Q: How do I stop the engines from using LH2/O and use LF/O instead? A: Install the CryoEnginesLFO patch in the Extras folder.

Dependencies (Required and Bundled) Module Manager  B9 Part Switch Community Resource Pack Cryo Tanks Deployable Engines Dynamic Battery Storage Licensing All code and cfgs are distributed under the MIT License All art assets (textures, models, animations) are distributed under an All Rights Reserved License. All bundled mods are distributed under their own licenses.

Download Mirrors

Primary (SpaceDock) Secondary (CurseForge) Tertiary (GitHub)

Issue Tracking and Source

Special Thanks

A big hand to Fraz86, who basically wrote the configs for fuel switching and balancing LH2 tanks :D.

If you appreciate this project, please consider contributing to my caffeine addiction! I really appreciate it, and also helps justify this time sink to my wife , which results directly in more models.

very nice, but when I use this mod, there are NO plumes, and NO sound!!?? What am I doing wrong?

[Nertea]

Typically you have installed a plume mod that is not up to date. Verify the up to date nature of CE and Waterfall and/or RealPlume.

[Rakete]

@Nertea: Bugreport - Type: Visual. Severity: Minor/Medium

Waterfall-Plume of Tharsis Engine does not move with engine gimbal movements:

Other engines of CE not checked for this. Not gamebreaking, not critical but visible.

Edited August 15, 2021 by Rakete

[Rakete]

@Nertea: Bugreport - Type: Calculations, Severity: Medium

DeltaV-Calculations of a stage oscillates in orbit. Observed with Tyrannosaur (CE) and Scylla (KA) engine.

Testcase launch one of the linked vessels into orbit and watch the dV-Calculations of 1. stage in orbit when tanks pretty emptied after launch:

https://www.filemail.com/d/bvgcnbxmpzenyxz

This dV oscillation causes oscillation of the ingame burn indicator, when to start a burn and makes precise burns difficult.

 

Tested with newest versions of KA, SH, CE, etc.

 

EDIT: Further investigation: Tested also via cheat to orbit: dV readings oscillate also with filled tanks. Oscillation stops if I re-enable the cooling of the 1st stage tanks (which had disabled cooling on big S3-stock tanks, as it was not neccessary for a first stage to cool it, as the boil of is negligable during launch of a first stage).  So it seems to have to do with the CryoTanks-Boil-off-mechanic, and should be moved over to the CT-Thread... Sorry, but I noticed this root cause only after further investigation this evening and initially thought it was the engine's fault, not the tank's. )

EDIT 2:  Oscillation starts already on launchpad as soon, as the starting clamps are disengaged and engine is turned on (zero throttle) on the given example vehicles (Arakis Station Part 2). In order to not spam your threads (You can't delete posts in this forum, somehow...), please pick up the issue here, so i won't have to copy the issue to the CT-Thread. Unfortunately I still can not login to github. So yeah, maybe you want to copypaste the issue to github yourself - or somebody here would please be so kind ?! Sorry, for that. As cooling engaging prohibits this bug I switched the rating from major to medium. :-)

Edited August 16, 2021 by Rakete

[linuxgurugamer]

@Nertea

Something strange is happening on one of the engines.

My mod, KSP_PartVolumes, gets the size of each part from the  renderer bounds.

For some reason, this part is reporting bounds which are huge:

// ----------------------------------------------------------------------
// CryoEngines/Parts/MethaloxEngines/1875/cryoengine-iguanodon-1/cryoengine-iguanodon-1
// Dimensions: x: 25.98, y: 5.77, z: 25.98
// Bounding Box Size: 3892503 liters

I'm not sure why, wondering if anything changed recently in the part.  This is apparently the only engine that's showing this issue.

Would you have any idea?

[Nertea]

1 minute ago, linuxgurugamer said:

I'm not sure why, wondering if anything changed recently in the part.  This is apparently the only engine that's showing this issue.

 

Sometimes Unity throws a fit on calculating the bounding box of skinned mesh renderers. I've been unable to determine why. 

[linuxgurugamer]

5 minutes ago, Nertea said:

Sometimes Unity throws a fit on calculating the bounding box of skinned mesh renderers. I've been unable to determine why. 

Strange.  It's consistent, happens every time, from what I can tell, this part only

[Nertea]

3 hours ago, Rakete said:

@Nertea: Bugreport - Type: Calculations, Severity: Medium

DeltaV-Calculations of a stage oscillates in orbit. Observed with Tyrannosaur (CE) and Scylla (KA) engine.

Testcase launch one of the linked vessels into orbit and watch the dV-Calculations of 1. stage in orbit when tanks pretty emptied after launch:

https://www.filemail.com/d/bvgcnbxmpzenyxz

This dV oscillation causes oscillation of the ingame burn indicator, when to start a burn and makes precise burns difficult.

 

Tested with newest versions of KA, SH, CE, etc.

 

EDIT: Further investigation: Tested also via cheat to orbit: dV readings oscillate also with filled tanks. Oscillation stops if I re-enable the cooling of the 1st stage tanks (which had disabled cooling on big S3-stock tanks, as it was not neccessary for a first stage to cool it, as the boil of is negligable during launch of a first stage).  So it seems to have to do with the CryoTanks-Boil-off-mechanic, and should be moved over to the CT-Thread... Sorry, but I noticed this root cause only after further investigation this evening and initially thought it was the engine's fault, not the tank's. )

EDIT 2:  Oscillation starts already on launchpad as soon, as the starting clamps are disengaged and engine is turned on (zero throttle) on the given example vehicles (Arakis Station Part 2). In order to not spam your threads (You can't delete posts in this forum, somehow...), please pick up the issue here, so i won't have to copy the issue to the CT-Thread. Unfortunately I still can not login to github. So yeah, maybe you want to copypaste the issue to github yourself - or somebody here would please be so kind ?! Sorry, for that. As cooling engaging prohibits this bug I switched the rating from major to medium. :-)

I wasn't able to reproduce this. Here is the test rig i used (I didn't notice your craft, I will try again with the specific craft sometime later):

Here is the engine 'state', I tried off, on, both modes, etc. In each case the lower left DV changed as appropriate (lower with augmented mode, etc) but didn't fluctuate. 

 

2 minutes ago, linuxgurugamer said:

Strange.  It's consistent, happens every time, from what I can tell, this part only

It's not on occasion, it's on some meshes. 

[linuxgurugamer]

I see.  So I just tried using the collider bounds, and it's still strange, this time I got the following:

// Dimensions: x: 0.00, y: 2.53, z: 0.00

 

[Nertea]

13 minutes ago, linuxgurugamer said:

I see.  So I just tried using the collider bounds, and it's still strange, this time I got the following:

// Dimensions: x: 0.00, y: 2.53, z: 0.00

 

I'm not sure what would be up, it looks fine in Unity and the same using DebugStuff to me. 

[linuxgurugamer]

47 minutes ago, Nertea said:

I'm not sure what would be up, it looks fine in Unity and the same using DebugStuff to me. 

Really?  That will help, thanks.

I didnt see the dimensions I'l n DebugStuff. Will have to look again 

[Nertea]

Just now, linuxgurugamer said:

I didnt see the dimensions I'l n DebugStuff. Will have to look again 

Uh just to note I didn't look at dimensions, I'm purely observing that the collider meshes are visually correct. 

[linuxgurugamer]

28 minutes ago, Nertea said:

Uh just to note I didn't look at dimensions, I'm purely observing that the collider meshes are visually correct. 

I see.  Ok, that's what I saw as well.  But I'll see if DebugStuff is getting other info somehow

[Rakete]

10 hours ago, Nertea said:

I wasn't able to reproduce this. Here is the test rig i used (I didn't notice your craft, I will try again with the specific craft sometime later):

Here is the engine 'state', I tried off, on, both modes, etc. In each case the lower left DV changed as appropriate (lower with augmented mode, etc) but didn't fluctuate. 

 

It's not on occasion, it's on some meshes. 

Please use two or more big s3-tanks (or another big (!) equivalent from your non-cryo-tanks) filled with cryo fuel but without activated cooling and a matching engine e.g. tyrannosaur or scylla. I could not reproduce it with real cryotanks on two attempts - so it might be caused by the bigger boiloff values of conventional tanks that are filled with crygenic fuels and not cooled. Just activate the engine (maybe fire a bit) and stop it to zero throttle. The calculated dV is not stable and oszillates between two values, when the engine is not firing (0 throttle, but engine activated). The oscillation stops as soon as you activate cooling on both s3 (non-cryo)tanks. If you activate it on only one, the oscillation slows down. 

You can also use the craft (arakis station 2), that i provided above, remove the start clamps, cheat it into orbit, activate engine and set it to zero throttle. See the dV calc on the lefthandside switch beween two values for the first stage. For me 100% reproducable. The second stage does not osczillate since it uses real cryotanks with enganged cooling.

My guess: the boil off calculations interfere with stock dV calculations as soon as you have a tank or set of tanks that have a boiloff, that is big enough and an active but not firing engine on it (The oscillations are there also when the engine fires, but are much more difficult to observe, so do the test at zero throttle.)

 

This oscillation is problematic, if you do burns, that require a staging in the middle of the burn, as this oscillation of dV of 1st stage has affect on the burn start indicator and the staging moment prediction, which oscillates then as well between two points.

Edited August 17, 2021 by Rakete

[Nertea]

9 hours ago, Rakete said:

Please use two or more big s3-tanks (or another big (!) equivalent from your non-cryo-tanks) filled with cryo fuel but without activated cooling and a matching engine e.g. tyrannosaur or scylla. I could not reproduce it with real cryotanks on two attempts - so it might be caused by the bigger boiloff values of conventional tanks that are filled with crygenic fuels and not cooled. Just activate the engine (maybe fire a bit) and stop it to zero throttle. The calculated dV is not stable and oszillates between two values, when the engine is not firing (0 throttle, but engine activated). The oscillation stops as soon as you activate cooling on both s3 (non-cryo)tanks. If you activate it on only one, the oscillation slows down. 

You can also use the craft (arakis station 2), that i provided above, remove the start clamps, cheat it into orbit, activate engine and set it to zero throttle. See the dV calc on the lefthandside switch beween two values for the first stage. For me 100% reproducable. The second stage does not osczillate since it uses real cryotanks with enganged cooling.

My guess: the boil off calculations interfere with stock dV calculations as soon as you have a tank or set of tanks that have a boiloff, that is big enough and an active but not firing engine on it (The oscillations are there also when the engine fires, but are much more difficult to observe, so do the test at zero throttle.)

 

This oscillation is problematic, if you do burns, that require a staging in the middle of the burn, as this oscillation of dV of 1st stage has affect on the burn start indicator and the staging moment prediction, which oscillates then as well between two points.

I can reproduce this now under some very specific conditions and not at allin others, so this will be a tough one to fix. I now have a minimum viable test case that works at least though, so thanks. 

[Rakete]

3 hours ago, Nertea said:

I can reproduce this now under some very specific conditions and not at allin others, so this will be a tough one to fix. I now have a minimum viable test case that works at least though, so thanks. 

Yeah, as i said: since activation of cooling stops the bug, it's not a major thing. Just thought making the algorithm more robust to singularites at certain values is always kinda good. The usecase of not-cooled first lifter stages might be a viable one...

 

Edited August 17, 2021 by Rakete

[Nertea]

2 hours ago, Rakete said:

Yeah, as i said: since activation of cooling stops the bug, it's not a major thing. Just thought making the algorithm more robust to singularites at certain values is always kinda good. The usecase of not-cooled first lifter stages might be a viable one...

 

After 3 hours of investigation, I've determined this is a bug in the stock DV calculator. The code that operates the boiloff has been optimized as a result of this work though so it wasn't for nothing. Both the MechJeb and KER calculators don't have an issue with this, so my recommendation is that anyone who really cares about this specific issue use one of the better calculators. 

[frostdillicus]

Really enjoying the mod so far. It definitely adds some neat new considerations that stock engines do not. However, I am having a hard time with design using the engines and associated fuels.

When I build lifters using the stock LF/O engines they are super stable. When I use the cryo engines and LH2/O I seem to always get insane SAS wobble. My rockets are indeed longer to accommodate the extra fuel requirements however they aren't any longer than anything I have made using stock LF/O parts. 

Are there extra design considerations I need to be aware of when using the cryo engines and fuels?

I'm at a loss so I figured I might get some advice from people who have been using it longer than I have.

Thanks!